How do you add a beta code authentication to a rails site?

I have two different pages, one is to enter the beta code, and the other is to actually sign up. Before gaining access to the signup page one must first enter a correct beta key.

How can I check the input, when the user clicks the submit button, with a list of 开发者_如何学编程beta keys and then redirect to the sign up page. What I actually want to do is call a helper when the user clicks submit that is able to take the info from the beta code textbox.

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What you're looking for is called whitelisting. See Whitelisting with devise for examples.